Telescopes and Instrumentation
The Virtual Observatory in Europe and at ESO
Paolo Padovani, Peter Quinn (ESO)
Three science demonstrations
Virtual Observatories are moving from a
“research and development” to an
“operational” phase. We report on the
EURO-VO, a project to build an operational Virtual Observatory in Europe,
and on the new Virtual Observatory Systems department at ESO.
These were held on an annual basis, in
coordination with the IVOA, for the AVO
Science Working Group (SWG), established to provide scientific advice to
the project. Three very successful demonstrations were held in January 2003
(Jodrell Bank), 2004 (ESO, Garching),
and 2005 (ESAC, Madrid).
The Virtual Observatory (VO) is an innovative, evolving system, which will allow
users to interrogate multiple data centres
and services in a seamless and transparent way, to best utilise astronomical data.
The main goal of the VO is to enable
new science by making the huge amount
of data currently available easily accessible to astronomers. The VO initiative is a
global collaboration of the world’s astronomical communities under the auspices
of the recently formed International Virtual
Observatory Alliance (IVOA; http://ivoa.net;
see Figure 1).
The Astrophysical Virtual Observatory
The status of the VO in Europe is very
good. In addition to seven current national
VO projects, the European funded collaborative Astrophysical Virtual Observatory
(AVO) project had the task of creating the
foundations of a regional-scale infrastructure by conducting a research and demonstration programme on the VO scientific
requirements and necessary technologies. The AVO had been jointly funded by
the European Commission (under the
Fifth Framework Programme [FP5]) with
six European organisations (ESO, the
European Space Agency [ESA], AstroGrid,
the Centre de Données astronomique
de Strasbourg [CDS], TERAPIX, and
Jodrell Bank) participating in a three-year,
Phase-A work programme.
First VO paper
We reported last year (Padovani et al.
2004 b) on AVO’s second demonstration,
held on January 27–28, 2004 at ESO,
which led to the discovery of 31 new optically faint, obscured quasar candidates
(the so-called QSO 2) in the two Great Observatories Origins Deep Survey (GOODS)
fields. These results, in turn, led to the
publication of the first refereed astronomical paper enabled via end-to-end use
of VO tools and systems (Padovani et al.
2004 a). The paper was also publicised
by an ESA /ESO press release (see
http://www.euro-vo.org/pub/articles/
AVO1stSciencePressRelease.html).
tion of image and catalogue data, and
remote calculations in a fashion similar to
remote computing. The AVO prototype is
a VO tool which can be used now for
the day-to-day work of astronomers and
can be downloaded from the AVO Web
site as a Java application. We note that
this is by definition a prototype and will
not be maintained on the long term. Most
of the functionalities developed for the
AVO demonstrations are now available in
the public version of Aladin, and the inclusion of the remaining ones is being assessed.
Science Reference Mission
The Science Reference Mission is a definition of the key scientific results that the
full-fledged VO in Europe should achieve
when fully implemented. It consists of a
number of science cases, with related requirements, against which the success
of the operational VO in Europe will be
measured. It was put together by the AVO
SWG.
VO tools
For the purpose of the demonstrations
progressively more complex AVO demonstrators have been constructed. The
current one is an evolution of Aladin, developed at CDS, and has become a set of
various software components, provided
by AVO and international partners, which
allows relatively easy access to remote
data sets (images and spectra), manipula-
The AVO was also a founding member of
the IVOA, and has provided fundamental input for the development of VO standards and their usage.
The AVO project is now formally concluded. Links to various documents and
to the software download page can be
found at http://www.euro-vo.org/twiki /
bin /view /Avo /.
The AVO project was driven by a strategy
of regular scientific demonstrations of
VO technology and is now formally concluded. AVO’s main achievements can
be thus summarised:
Figure 1: The International Virtual Observatory
Alliance, the Member Organisations.
22
The Messenger 122 – December 2005
The EURO-VO
The EURO-VO work programme is the
logical next step from AVO as a Phase-B
deployment of an operational VO in Europe. Building on the development experience gained within the AVO Project, in
coordination with the European astronomical infrastructural networks OPTICON
and RADIONET, and through membership
and support of the IVOA, EURO-VO will
seek to obtain the following objectives:
(1) technology take-up and full VO compliant data and resource provision by astronomical data centres in Europe; (2) support to the scientific community to utilise
the new VO infrastructure through dissemination, workshops, project support,
and VO facility-wide resources and services; (3) building of an operational VO infrastructure in response to new scientific
challenges via development and refinement of VO components, assessment of
new technologies, design of new components and their implementation. EUROVO is open to all European astronomical
data centres. Initial partners include
ESO, the European Space Agency, and
six national funding agencies, with their
respective VO nodes: Istituto Nazionale di
Astrofisica (INAF, Italy), Institut National
des Sciences de l’Univers (INSU, France),
Instituto Nacional de Técnica Aeroespacial (INTA, Spain), Nederlandse Onderzoekschool voor Astronomie (NOVA, the
Netherlands), Particle Physics and Astronomy Research Council (PPARC, United
Kingdom), and Rat Deutscher Sternwarten (RDS, Germany). The total planned
EURO-VO resources sum up to approximately 60 persons per year over three
years, i.e., about three times those of the
AVO.
EURO-VO will seek to obtain its objectives by establishing three new interlinked
structures: 1. the EURO-VO Data Centre
Alliance (DCA), an alliance of European
data centres who will populate the EUROVO with data, provide the physical storage and computational fabric and who will
publish data, metadata and services
to the EURO-VO using VO technologies;
2. the EURO-VO Facility Centre (VOFC),
an organisation that provides the EUROVO with a centralised registry for resources, standards and certification mechanisms as well as community support
for VO technology take-up and dissemi-
nation and scientific programme support
using VO technologies and resources; 3.
the EURO-VO Technology Centre (VOTC),
a distributed organisation that coordinates
a set of research and development projects on the advancement of VO technology, systems and tools in response to
scientific and community requirements.
The DCA will be a persistent alliance of
data centre communities represented at a
national level. Through membership in
the DCA, a nation’s community of data
curators and data service providers will be
represented in a forum that will facilitate
the take-up of VO standards, share best
practice for data providers, consolidate
operational requirements for VO-enabled
tools and systems and enable the identification and promotion of scientific requirements from programmes of strategic
national interest that require VO technologies and services. Funds for the DCA
have been requested in an FP6 proposal
submitted in September 2005.
The VOFC will provide a “public face” to
the EURO-VO. Through outreach, support
of VO-enabled science projects in the
community, workshops and schools, the
VOFC will represent a central support
structure to facilitate the broad take-up of
VO tools by the community. The VOFC will
also support the EURO-VO Science Advisory Committee (SAC) to ensure appropriate and effective scientific guidance
from the community of leading researchers
outside the mainstream VO projects. The
SAC will provide an up-to-date stream
of high-level science requirements to the
EURO-VO. The VOFC will further provide
central services to the DCA for resource
registry, metadata standards and EUROVO access. Funding for the VOFC has yet
to be fully defined but will come initially
from ESO and ESA with activities ramping
up in 2006. The first VOFC activity was
the organisation of the EURO-VO workshop at ESO Headquarters in Garching
from June 27 to July 1, 2005 (Padovani &
Dolensky 2005).
The VOTC will consist of a series of coordinated technology research and development projects conducted in a distributed
manner across the member organisations.
The first project under the VOTC is the
VO-TECH project, funded through the EC
FP6 Proposal and contributions from the
Universities of Edinburgh, Leicester, and
Cambridge in the United Kingdom,
ESO, CNRS and Université Louis Pasteur
(France), and INAF (Italy). Additional
projects can be brought to the VOTC via
other member organisations; one such
example is ESA-VO. The VOTC provides
a mechanism to coordinate and share
technological developments, a channel for
DCA and VOFC requirements to be addressed and for technological developments to be distributed to the community
of data centres and individual scientists in
a coordinated and effective manner.
The EURO-VO project will be proactive in
reaching out to European astronomers.
As a first step, the EURO-VO has started
making regular appearances at Joint European and National Astronomy Meetings
(JENAM), as of the one in Liège in July
2005.
VO and ESO
Data centres have a major role in the VO,
as they are the primary source of astronomical data. The VO cannot (and does
not) dictate how a data centre handles
its own archive. However, a “VO-layer” is
needed to “translate” any locally defined
parameter to the standard (i.e., IVOA
compliant) ones. For example, right ascension can be defined in different ways
by different data centres but the VO user
needs to know which of the many parameters accessible through an archive interface is the right ascension. The longerterm vision of the VO is also to hide away
any observatory/telescope/instrument
specific detail and work in astronomical
units, for example, “wavelength range” and
not grism or filter name. Data providers
are then advised to systematically collect
metadata (“data about data”) about
the curation process, assign unique identifiers, describe the general content (e.g.,
physical coverage) of a collection, and
provide interface and capability parameters of public services. Finally, the VO
will work at its best with high-level or “science-grade” data, so that the VO user is
spared as much as possible any complex
and time-consuming data reduction.
Data centres should then make an effort
to provide such data.
The Messenger 122 – December 2005
23
Telescopes and Instrumentation
Padovani P., Quinn P., The Virtual Observatory in Europe and at ESO
All these issues obviously affect ESO as
well. To address them, the Data Management and Operations Division created
the Virtual Observatory Systems (VOS)
Department on November 1, 2004. VOS’
role is to manage ESOs involvement in
VO activities and to make the Science
Archive Facility (SAF) into a powerful scientific resource for the ESO community.
The new department, headed by Paolo
Padovani, includes, at present, the Virtual
Observatory Technology (VOT) and the
Advanced Data Products (ADP) groups,
led respectively by Markus Dolensky and
Piero Rosati, and is made up of thirteen
people.
(VST; Cappellaro 2005; Capaccioli et al.
2005) and from VISTA (Emerson et al.
2004);
3. Publication of ADP within the VO infrastructure; this will require a complete redesign of the SAF and of its interface. As
a first step in that direction, on the occasion of the opening of the ESO archive to
the world on April 4, 2005, VOS has deployed a redesigned archive interface. Its
aim is to facilitate data queries to archival users who might not be familiar with
ESO instruments. The new interface is accessible at http://archive.eso.org/eso/
eso_archive_main.html;
4. Development of VO technology, standards, and tools for the ESO SAF, also via
participation to European VO activities,
in particular through the VOTech project.
References
Capaccioli, M., Mancini, D., Sedmak, G. 2005,
The Messenger 120, 10
Cappellaro, E. 2005, The Messenger 120, 13
Emerson, J. P. et al. 2005, The Messenger 117, 26
Padovani, P. et al. 2004a, A&A 424, 545
Padovani, P. et al. 2004b, The Messenger 117, 58
Padovani, P., Dolensky, M. 2005, The Messenger 121,
60
The specific tasks of VOS are
the following:
1. Creation of ADP, i.e., science-ready
(“level-3” in ESO terms) data products
from the ESO archive; this will be done by
using a redesigned imaging pipeline built
on top of the EIS/MVM software and
also via a coordinated activity between the
ADP and the Data Flow System (DFS)
groups to single out possible upgrades of
specific DFS pipelines from level-2 to
level-3. A recent ADP effort has been the
processing via the EIS/MVM software and
release of the ISAAC/GOODS data,
which include 11600 science frames and
10 600 calibration frames, photometrically calibrated using pre-determined zero
points from SOFI data. These data are
available at http://www.eso.org/science/
goods/releases/20050930/ (see Figure 2);
2. Ingestion of ADP into a VO-compliant
SAF; these will include not only products
generated by the ADP group but also
by the community. For example, scienceready data products from a number
of ESO projects, which are currently available in a heterogeneous fashion from
customised web pages. In particular, as
of Period 75 PIs of Large Programmes
are requested to provide ESO with their
reduced data products at the time of publication of their results. Moreover, Public
Survey data products will also be ingested and published in a VO-compliant way,
as they will be extremely useful to VO users, being highly homogeneous and well
calibrated. These will include data from
OmegaCAM on the VLT Survey Telescope
24
The Messenger 122 – December 2005
Figure 2: JHK colour composite of the ISAAC/GOODS
mosaic part of the latest Advanced Data Products
group of the Virtual Observatory Systems (VOS) Department release, which includes 21 tiles in the J-, Hand Ks-bands, and five additional tiles in the J- and
Ks-bands (not visible in this image). Each ISAAC field
is 2.5 arcmin across. See http://www.eso.org/
science/goods/releases/20050930/